<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="js/jquery-1.11.2.min.js"></script>
</head>
<body>
<script>
function imgShow(_this){
var src = _this.attr("src");
$("#bigimg").attr("src", src);
$("<img/>").attr("src", src).load(function(){
var windowW = $(window).width();
var windowH = $(window).height();
var realWidth = this.width;
var realHeight = this.height;
var imgWidth, imgHeight;
var scale = 0.8;

if(realHeight>windowH*scale) {
imgHeight = windowH*scale;
imgWidth = imgHeight/realHeight*realWidth;
if(imgWidth>windowW*scale) {
imgWidth = windowW*scale;
}
} else if(realWidth>windowW*scale) {
imgWidth = windowW*scale;
imgHeight = imgWidth/realWidth*realHeight;
} else {
imgWidth = realWidth;
imgHeight = realHeight;
}
$("#bigimg").css("width",imgWidth);

var w = (windowW-imgWidth)/2;
var h = (windowH-imgHeight)/2;
$("#innerdiv").css({"top":h, "left":w});
$("#outerdiv").fadeIn("fast");
});
$("#outerdiv").click(function(){
$('#outerdiv').fadeOut('fast');
});
}
</script>
<div id="outerdiv" style="position:fixed;top:0;left:0;background:rgba(0,0,0,0.7);z-index:999;width:100%;height:100%;">
    <div id="innerdiv" style="position:absolute;">
        <img id="bigimg" style="border:5px solid #fff;" src="img/TB22XgSdlNkpuFjy0FaXXbRCVXa_!!0-paimai.jpg" onclick="imgShow(this)" />
    </div>
</div>
</body>
</html>